sounds like it's causing an import error perhaps? I think that if you don't have a spatial backend the error is better, but have you confirmed that you do have a working geospatial backend?
–
Skylar SavelandDec 1 '09 at 23:09

Links to psycopg2 and GeoDjango given on GeoDjango installation instructions page rely on Postgres 8.3,

So, if you use Postgres 8.4 you must install appropriate version of psycopg2 from here also GeoDjango installer modifies the system Path environment variable to include C:\Program Files\PostgreSQL\8.3\bin.

In case of Postgres 8.4 you must change Path variable to C:\Program Files\PostgreSQL\8.4\bin.